Prop Shaft Connection to VD Trans

It depends on how long you had to 'limp' home.

If the shaft on the stalled engine continues to turn for a long period you can overheat the seal and shorten it's life. May not be something you would see right of way.

Also, and crossover doesn't solve/help this, you have to worry about your transmission. DIfferent manufacturers have different criteria and specs when 'freewheeling'.

Isn't crossover where you are moving water from the running engine "over" to the other transmission? If yes, why doesn't it help? I am not an expert on this, just recently heard about it, learning as I go.
 
Water injection for the shaft seals is necessary on planing hulls since when planing, there may be no water in contact with the seal unless it is supplied via a tube. However when the boat is not running at planing speeds the shaft seal should be surrounded by water. Since our boats can't plane on one engine, a crossover isn't necessary since the seal should already be wet from water surrounding the boat.

The crossover helps ensure that water from either engine will cool the seals in the event of a problem with the raw water side. Better just an overheat than an overheat and burned up shaft seals.

Best regards,
Frank
 
Water injection for the shaft seals is necessary on planing hulls since when planing, there may be no water in contact with the seal unless it is supplied via a tube. However when the boat is not running at planing speeds the shaft seal should be surrounded by water. Since our boats can't plane on one engine, a crossover isn't necessary since the seal should already be wet from water surrounding the boat.

The crossover helps ensure that water from either engine will cool the seals in the event of a problem with the raw water side. Better just an overheat than an overheat and burned up shaft seals.

Best regards,
Frank

So why the need to lock down the shaft if it's not getting a raw water supply while idling/hull speeding? Maybe I misunderstood your reply.
 
On my 1993 330DA, without dripless seals, there was a collar on the shaft under the hull just before the shaft tube. The purpose of that collar, as it was explained to me, was the deflect water back into the shaft to cool the shaft and packing.

When traveling at 5-7 knots on one engine, without that collar, I don't see how any water could get injected up into the seal and provide any cooling to the seal.
 
5 knots is probably OK. Faster displacement speeds could pull the water from the seal. I guess it depends on how slowly one limps.

Best regards,
Frank
 
Isn't crossover where you are moving water from the running engine "over" to the other transmission? If yes, why doesn't it help? I am not an expert on this, just recently heard about it, learning as I go.

No....the crossover brings water from one seal to the other seal....not the transmissions.

If both motors are running each motor is supplying cooling water the seals. If only one motor is running, the running motor is supplying cooling water to both seals.
 
No....the crossover brings water from one seal to the other seal....not the transmissions.

If both motors are running each motor is supplying cooling water the seals. If only one motor is running, the running motor is supplying cooling water to both seals.

Correct, I meant the seals, not the trans. My understanding of a crossover is to keep raw water supplied to the shaft seal if that shaft's raw water supply stops, for example no running engine.

We limped at 5-6 kts, so w/dripless shafts are we OK (were we OK) to not lock down the shaft?

I am noticing a small amount of water (maybe a gallon) under the port transmission after a cruise. If I vacuum it up before we leave the boat it''s not there when we return, but appears again after a cruise.
 
I think it is 1 1/4". When I bought the boat I had the wheels off to have it hauled. I sent the wife to Sears with one of the nuts and told her to get me an open end wrench and a 3/4" socket to fit. I keep both the wrench and the socket along with a 3/4" to 1/2" adapter and a 1/2" rachet in my tool box on board.
 
........
We limped at 5-6 kts, so w/dripless shafts are we OK (were we OK) to not lock down the shaft?

I am noticing a small amount of water (maybe a gallon) under the port transmission after a cruise. If I vacuum it up before we leave the boat it''s not there when we return, but appears again after a cruise.

I think you answered your own question.

I am dry under my seals....very dry.
 
I think you answered your own question.

I am dry under my seals....very dry.

Not necessarily, lots of "water things" on that side of the boat. In fact, I just replaced a fresh water t-fitting that was spraying on that side plus I am seeing rust at the bottom of the water heater.

How can one confirm their shaft seal is leaking?
 
The crossover water feed costs almost nothing if you are buying new seals. If you never will need to run the boat several miles on one engine then you don't need it. Unfortunately, you never know when or where the need to come home on one will occur, so crossover cooling may save you the cost of a seal assembly and haul out when you only lost a fuel pump or clogged up a fuel fiter. A haulout and seal assy replacement won't leave any change from a $1000 bill. Compared to a $10 fuel filter, that is an easy decision point for me.

These seals have a hard plastic body, something like Delrin, and they will not tolerate being run dry. Dead in the water and they may have enough water around them to cool, but when forward motion begins a vacuum is created behind the shaft log and at some point, the seal is going to run dry and get hot........whether that is 2 kts or 12 kts depends on the boat.

The reason you tie off a shaft when you run a good distance on one engine is to save wear and tear on the transmission bearings, gears, seals and most of all the clutch pack since the transmission pump isn't generating any pressure when the engine isn't running.
 
The crossover water feed costs almost nothing if you are buying new seals. If you never will need to run the boat several miles on one engine then you don't need it. Unfortunately, you never know when or where the need to come home on one will occur, so crossover cooling may save you the cost of a seal assembly and haul out when you only lost a fuel pump or clogged up a fuel fiter. A haulout and seal assy replacement won't leave any change from a $1000 bill. Compared to a $10 fuel filter, that is an easy decision point for me.

These seals have a hard plastic body, something like Delrin, and they will not tolerate being run dry. Dead in the water and they may have enough water around them to cool, but when forward motion begins a vacuum is created behind the shaft log and at some point, the seal is going to run dry and get hot........whether that is 2 kts or 12 kts depends on the boat.

The reason you tie off a shaft when you run a good distance on one engine is to save wear and tear on the transmission bearings, gears, seals and most of all the clutch pack since the transmission pump isn't generating any pressure when the engine isn't running.

I know we are getting a little OT here, tell me to stop if we are...

Where is this seal? I can see, in the engine compartment, where the shaft goes thru the hull, my assumption is it's there. Secondly, the raw water flow to it, where? I see raw water hoses running to the trans but I have never seen a raw water hose running to the shaft area.
 
Confirm the shaft seal leak by looking at it........the wet stuff belongs outside the boat.

Actually, when a Tides seal begins to fail, they don't leak when sitting idle. The only leak when underway with the shaft turning. So if you are in the beginning stages of a lip seal failure, you will only see the leak when running. But, this is a slippery slope.......once a seal begins to leak, they just get worse, never better. Sooner or later the seal will drip all the time.......then a little later still, it won't be a drip but a steady stream. The trick is to get it to last until you need to haul out for some regular bottom maintenance so that you don't have to spent $400 to haul out just to replace a $400 seal.
 
This shaft was replaced 7 months ago from the log that hit us. Our mechanic told us the seal looked good when he did the replacement. Can you tell by looking at it, on land, I assume with the shaft out, that it looked good? I did tell him about the water on that side of the boat after the shaft install and he said the shaft seal was in good shape, not leaking.

The water was present before/after the shaft replacement so nothing about the replacement made it better/worse.
 
John

Wow what great advice, man it pays to learn from experience. After reviewing all the various options available to replace the Strong Seals I am sold on the PSS design and glad you agree. I have reviewed the instructions that PSS has posted on their website, but yours are even more detailed. As far as a water source, I already have that in place with the Strong Seals so I am going to just reuse the same hoses. I appreciate your advice to completely remove the shafts. I figured when you said they only had to be pulled back 5" you were forgetting I have the V drives. How should I connect my slide hammer to the shaft at the prop end to pull the shaft of do you think I am not need the hammer at all?

Also do you think there is any value in having the shafts inspected while they are out at a shaft shop? I am thinking about have them checked for stress crackes and straightness?


Thank you for the compliment. I would have the shafts inspected at a shop and also cleaned. They can put it on a lathe and polish quickly, check the run-out and check it for cracks. It would make the assembly job a lot easier when the shaft surface has been cleaned....that is a really good idea. You may also want to take the hubs along. Make sure you match them with shafts.

After looking at the photo you sent, I believe you have enough room (got to love bigger boats) to use an automotive style harmonic balancer puller to push the shaft through the hub. If the shaft is not frozen, it should work fine. You proabably will only get two of the puller bolts to match up with the hub.....but that should be enough. Get a few long grade 8 bolts and nuts that will fit the puller and hub. Unbolt the hub from the transmission to give yourself some more flexibility in the process.

This way you won't have to weld a steel nut that matches the prop shaft threads on the end of your slide hammer!

I will let you guys debate the merits of a crossover hose........
 
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Just like Frank said, my port seal only leaks when running. After a day on the water I can shop vac about 2 gallons of water out of the bilge. If you put some dry towels under each seal before you go out for the day you can then recheck them at the end of the day and see which one is wet. Greg on your 330 I dont know if you can really get down there and do this, it is my understanding that on the 330 or smaller you usually have to pull the engine to work on these seals. Lucky for me on the 370 you can get right to them without too much trouble.

Just called Atlantis Propellor http://www.atlantispropeller.com/index.html who did my wheels. They said they will clean, inspect and make minor repairs to the shafts for $80 each..... for that price they are going in. They also said they have a new service where the will clean and do a minor check on the wheels for 1/2 the normal propscan cost which for me is about $200 per wheel (full price)
 
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Just like Frank said, my port seal only leaks when running. After a day on the water I can shop vac about 2 gallons of water out of the bilge. If you put some dry towels under each seal before you go out for the day you can then recheck them at the end of the day and see which one is wet. Greg on your 330 I dont know if you can really get down there and do this, it is my understanding that on the 330 or smaller you usually have to pull the engine to work on these seals. Lucky for me on the 370 you can get right to them without too much trouble.

Just called Atlantis Propellor http://www.atlantispropeller.com/index.html who did my wheels. They said they will clean, inspect and make minor repairs to the shafts for $80 each..... for that price they are going in. They also said they have a new service where the will clean and do a minor check on the wheels for 1/2 the normal propscan cost which for me is about $200 per wheel (full price)

We just used WildCat Propellers in Chesapeake, VA for the first time on our 4 bladed props. $150 a prop with scan results. Mailed them in, back in under2 weeks.

They repaired the one we bent from the recent grounding after another shop said it could not be repaired.
 
wingless, The trick is getting the hub off the shaft. In the method you describe did you using a hub press (which connects to the hub with bolts and nuts) or did you use a shaft puller on the shaft that did not come off the hub easily?
Neither. As a life-long nutmegger I employed a BFH and imparted repeated impact force onto the shaft tip to break the joint.

The minor shaft tip blemishes were cleaned-up w/ a right angle-die grinder to better than new.

The before images showing the bore defects were all out-of-focus.

This after image shows the exterior cosmetic polishing of the steel hub. It also shows the bore clean-up, that removed all irregularities from the bore. My expectation is the next removal will be okay.

XMSNHubs.jpg
 
I have Tides Strong Seals on my SR, and a PSS on my single-screw Chris. I do like the PSS, but I have heard that there have been failures of the bellows (losing their elasticity over time).
I had the seals on my Tides replaced at last haulout, but when they go again I'm going to look into these:
http://www.lasdrop.com/products.php

They're what my yard recommends; the principle seems to be the same as the PSS seal, except that the pressure on the seals is exerted by a spring assembly instead of compressing the bellows on the PSS. Worth looking into, wonder if anyone here has experience with them...

Also, as was mentioned getting the coupler off the shaft can be problematic- a torch to heat up and expand the coupler can help. FYI the couplers are always fitted/machined to match the taper of of the shaft, so changing either one requires sending both to the machine shop. Good luck.
 
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